Gram-negative bacteria that are resistant to aminoglycoside, β-lactam, and fluoroquinolone antibiotics are increasingly common. These bacteria are often only susceptible to the polymyxins and related peptides having antibacterial properties. As a result, there is renewed interest in the use of polymyxins for the treatment of multidrug-resistant Gram-negative bacterial infections in humans.
Peptides such as polymyxin B and the related colistin (polymyxin E) have been administered to humans as antibacterial agents. However, their use has been previously limited because of their toxicity.
Thus, there is a need for new peptide compounds having equivalent antibacterial properties to polymyxin B with an improved therapeutic index, as well as methods of manufacturing such antibacterial compounds.